For gripping a workpiece by its inner diameter. Machine these arbors to hold a specific part. For use on lathes, milling machines, grinders, chucks, collets, fixtures, etc. How to Use: Chuck arbor in the machine to be used. Tighten expanding screw so that the arbor expands .005. Machine arbor to length and size required. Loosen expanding screw. Position the part on the arbor and tighten expanding screw.